Temperatures are set to plunge as low as -2C tonight as a cold snap grips the country.

London was well below freezing last night too, with mercury falling to as low as -3C.

This weekend freezing weather is set to blanket the country with up to four inches of snow.

Many parts of the UK will struggle to see temperatures go above freezing.

Motorists are being warned about freezing fog that formed overnight across the Midlands, East Anglia and central and southern England.

Areas in the south east and the North Sea coast have seen little more than a tiny amount of snow so far.

Snowfall yesterday led to 42 schools being closed in Norfolk and all planes grounded at Norwich International Airport.

The lowest temperatures overnight were -12.7C at Braemar in Scotland and -12.1C at Houghton Hall in Norfolk, according to forecasters.

Gemma Plumb, a forecaster with MeteoGroup, said it had been bitterly cold for much of the UK overnight - average temperatures were between -3C and -7C, and -3C in London - with worse to come.

"Most places are looking like they will be dry today, with some sunny spells around. But fog and low cloud could linger in places like the East Midlands and East Anglia, with further outbreaks of sleet and snow across parts of western Scotland," Ms Plumb said.

"But it is going to be very cold today, with many places struggling to see temperatures rising above freezing.

"Parts of Scotland, northern England, Wales, the Midlands and East Anglia will be looking at maximum temperatures of -1C or zero."

A weather front moving across the UK tomorrow night is set to bring the biggest snowfall of the winter.

Ms Plumb said: "At the moment we are looking at 5cm to 10cm (2in-4in) falling quite widely across the country on Friday, with more than that locally, especially across higher ground."

The bad weather yesterday caused havoc on transport networks. A six-vehicle pile-up on the A11 left three people injured, and the AA reported about 1,000 breakdowns an hour.

Darron Burness of the AA said motorists should take measures to prepare for the cold weather and coming snow.

"The main problem is flat or failed batteries, as the car's electrical system has to work much harder in the cold," he said.

"When you get in your car, switch off all the electrics before starting it - for example, blowers, lights and heated windscreen - and dip the clutch while starting to take some of the load off the starter motor and, in turn, the battery."

The Highways Agency also warned motorists to take extra care on slippery and icy roads.

Ms Plumb said the coldest area of the UK overnight was Braemar in Scotland, which reached minus 12.9C (8.8F) - equalling the chilliest day of the winter so far.